Female Athlete Triad / RED-S and Bone Health

Peak bone mass is typically achieved by early adulthood (~30 years old). If an athlete experiences prolonged energy deficiency and hormonal imbalance, they risk long-term osteopenia (low bone density) or osteoporosis, increasing the likelihood of fractures and early bone deterioration.

Stress fractures are small cracks in the bone caused by repetitive impact and insufficient recovery. They occur when bone breakdown outpaces bone repair, often due to low energy availability, poor nutrition, and estrogen deficiency.

What is the Female Athlete Triad?

The Female Athlete Triad is a medical condition commonly seen in physically active women and consists of three interrelated components:

Low Energy Availability (LEA)
- Occurs when calorie intake is too low to support both exercise and essential bodily functions.
- Can result from intentional dieting, disordered eating, or unintentional under-fueling.
Menstrual Dysfunction
- Functional hypothalamic amenorrhea (FHA): Menstrual cycles become irregular or stop entirely due to energy deficiency.
- Estrogen production declines, which directly impacts bone resorption and formation.
Low Bone Mineral Density (BMD)
- Chronic LEA and estrogen deficiency lead to decreased BMD, making bones fragile and more prone to fractures.

Relative Energy Deficiency in Sport (RED-S)

RED-S includes all aspects of the Triad but also affects:

Metabolic rate (slowed metabolism)
Cardiovascular function (increased risk of heart issues)
Immune function (higher risk of illness and infection)
Mental health (increased anxiety, depression, and fatigue)

How the Triad and RED-S Affect Bone Health

Energy Deficiency & Bone Formation
- Inadequate nutrition disrupts the bone remodeling process, reducing osteoblast (bone-building) activity while increasing osteoclast (bone-breaking) activity.
Estrogen & Menstrual Dysfunction
- Estrogen is crucial for inhibiting excessive bone resorption. When estrogen levels drop due to energy deficiency, bone loss accelerates, leading to fragile bones.
Cortisol & Bone Resorption
- Chronic energy deficiency increases cortisol (stress hormone) levels, which further promotes bone breakdown and reduces calcium absorption.

How are the Triad and RED-S addressed?

Nutrition & Energy Balance
- Regular monitoring of menstrual cycles as a key indicator of health.
- In some cases, hormone therapy or dietary adjustments may be needed to restore balance.
Menstrual & Hormonal Monitoring
- Estrogen is crucial for inhibiting excessive bone resorption. When estrogen levels drop due to energy deficiency, bone loss accelerates, leading to fragile bones.
Bone Health Strategies
- Weight-bearing and strength-training exercises to stimulate bone growth.
- Avoiding excessive exercise without adequate recovery.
- Ensuring sufficient calcium (1,000–1,300 mg/day) and vitamin D (600–800 IU/day) intake.